Wang, Ligang
Xu, Lingyang
Liu, Xin
Zhang, Tian
Li, Na
Hay, El Hamidi
Zhang, Yuebo
Yan, Hua
Zhao, Kebin
Liu, George E
Zhang, Longchao
Wang, Lixian
Article History
Received: 27 March 2015
Accepted: 2 July 2015
First Online: 3 August 2015
Competing interests
: The authors declare no competing financial interests.